Each client can be given their own Account, that shows invoices and payments for their site, together with any other charges the reseller needs to make.
The account manages online payments, credit limits, and emails the client if they need to make payments. In extremis, it can even suspend their sites if they exceed their credit limit.
Site hosting
Read more about: Site Hosting
Template sites
As the server owner you can 'clone' a site to create a Template site, saving time on repeating development work, and enabling you to give your sites a consistent look or behavior.
Site creator

The Site Creator component allows a reseller's new clients to self-sign-up for a site, with the minimum of questions asked, and absolutely no interaction required by the reseller. The client is able to get started quickly with a reseller's template site, and can be given a free trial period before charging plans are applied to the account.